Completion method and system for wells



Sept. 28, 1965 c. B. coRLEY, JR

COMPLETION METHOD AND SYSTEM FOR WELLS Filed Nov. 14, 1965 AIIOBNEY- F'IG.4.

FI G. I.

United States Patent 3,208,529 COMPLETION METHOD AND SYSTEM FOR WELLS Charles B. Corley, Jr., New Orleans, La., assignor, by

mesne assignments, to Esso Production Research Company, Houston, Tex., a corporation of Delaware Filed Nov. 14, 1963, Ser. No. 323,742

This invention relates to oil and gas wells. More particularly, thisinvention is a method and system for removing tools from a well when the conventional methods and systems cannot be used to remove these tools because ofexcessive lost returns.

Certain operations are performed in oil and gas wells which require the uid circulation of pump tools. Pump tools, for example, maybe used extensively in completing submarine Wells. 'An example of an operation which may be performed by the use of pump tools is the installation or removal of a storm choke or subsurface safety valve from its position within a tubingstring placed in the well.

However, in order to properly utilize pump tools for removing subsurface devices by fluid circulation, it is necessary that excessive loss of the circulating fluid to the subsurface formations be prevented. If there is excessive loss of the circulating uid to the formations, sufficient pressure and circulating volume cannot be developed to circulate the pump tool and remove the subsurface devices.

The invention to be described herein provides the art with a method and system which can be used to prevent excessive loss of the circulating fluid to the formation during the removal of subsurface tools such as storm chokes.

The invention, as well as its many advantages, will be further understood by reference to the following detailed description and drawings in which:

FIG. 1 is a schematic, elevational view showing a storm choke in position within the well;

FIG. 2 is a schematic, elevational view showing the introduction of a dissolvable granular material for placement in the well to prevent excessive loss of circulation;

FIG. 3 is a schematic, elevational view showing the removal of a storm choke from the well after the dissolvable granular maten'al has been properly located; and

FIG. 4 is a schematic, elevational view illustrating the use of an acid dissolvable ball for preventing excessive loss of returns instead of the acid dissolvable granular material.

Referring to the drawings and more particularly to FIG. 1, a casing is shown cemented to the sides of a borehole by the usual cement 12. A tubing string 14 extends from the earths surface (not shown) to a point adjacent the subsurface producing formation 16. The usual perforations 19 have been made through casing 10, cement 12, and into producing formation 16 for the production of oils and gases from producing formation 16.

A tubing string 18 is also provided in the well. The tubing string 18 extends to a point within the Well adjacent the subsurface producing formation 16 and is used primarily to form a circulating path from the surface to the well bottom. Tubing string 18, serving as an alternate to tubing string 14, may also be used to conduct oils and gases produced from subsurface formation 16 to the earths surface. The usual packing 20 is provided about the tubing string 14 and tubing string 18.

The tubing strings 14 and 18 are uidly interconnected by a crossover or interconnecting line 22 located below the packing 20. The tubing string 14, interconnecting line 22, and tubing string 18 provide a fluid circulating 3,208,529 Patented Sept. 28, 1965 "ice path into and from the well. A retrievable plug 38 is placed in landing nipple 40 in tubing string 18 at a point below interconnecting line 22.

A landing nipple 24 is provided Within the tubing string 14. A storm choke 26 is provided with a bore 28 is shown positioned within the landing nipple 24. The usual seal 30 is provided about the storm choke 26.

A plurality of perforations 32 is formed adjacent the bottom of tubing string 14. If it is desired to remove the storm choke 26 with a pump tool circulated into the tubing string 14 from the earths surface, it is necessary that suicient circulating pressure be developed. There fore, a surface pressure test is conducted, as shown in FIG. 1, to estimate whether or not sufcient fluid pressure can be placed against the subsurface formation 16. If excessive fluid is lost to the subsurface formation 16 at low pressure, sufficient pressure cannot be maintained against the pump tool to remove the storm choke 26.

My new method and system can be used to remove thestorm choke 26 or other similar tools from the tubing string 14 when conventional methods and systems for removing these devices cannot be utilized because of excessive loss of circulating fluid to the subsurface formation. The perforations 32 are provided in tubing string 14 so that acid dissolvable granular material 34 (FIG. 2) may be pumped down the tubing string 14 through the bore 28 of storm choke 26 and into the bottom portion of tubing string 14 to pack olf the perforations 32. The tubing string 14 is closed at the bottom by plate 36 for this purpose.

Examples of acid dissolvable materials are calcium carbonate and aluminum. These materials may be dissolved by acids such as hydrochloric acid or acetic acid. The granular material may be placed into the well by mixing it with viscous fluids, such as oil-water emulsions or conventional drilling muds, in order that the granular material can be pumped as a slug to the proper position. The bridging of the granular material 34 against perforations 32 will sufliciently restrict loss of returns to permit application of adequate pressure against circulated pump tools to allow the storm choke 26 to be removed from the Well.

FIG. 3 illustrates the removal of the storm choke 26 from the tubing string 14 by means of reverse circulation after the pump tool 42 has been pumped into the tubing string 14 by direct circulation to engage the storm choke 26. The pump tool 42 is provided with knuckle joints 44 t-o permit pumping through curved tubular members and flow lines (not shown) located at the surface. As shown in FIG. 3, the pump tool has engaged the storm choke and is being removed upwardly through tubing string 14 by reverse circulation of lluid through tubing string 18, interconnecting line 22, and tubing string 14.

FIG. 4 shows an alternate to the use of granulated material with a perforated tubing. An acid dissolvable ball 46 is placed on the tapered seat 48 positioned Within the tubing string 14. The tapered seat 48 is located in a position similar to the location of the perforations 32 of FIGS. l through 3. The ball 46 can be made of aluminum or calcium carbonate and can be either porous or fluted to permit acid to be circulated to the bottom when it is desired that the ball be dissolved for restoration of the well to production.

In operation, if the storm choke 26 cannot be removed by conventional means because of loss of returns, the acid dissolvable granular material 34 is pumped down tubing string 14 to bridge the perforations 32. In the alternative, the acid dissolvable ball 46 can be dropped to the bottom of the well through tubing string 14. Thereafter, the pump tool 42 is directly circulated down tubing string 14 to engage storm choke 26. The pump tool 42 along with the storm choke 26 is then removed from the well by reverse circulation, The well can be returned to production by circulating acid, such as hydrochloric acid or acetic acid, to dissolve the granular material 34 or if the ball 46 is used, to dissolve the ball 46.

The method and system described herein has applicability to the use of tools other than storm Chokes in the well. Also, the method and system may be used to remove material, such as paraffin, by pumping a plug into and from the Well.

I claim:

1. A method of removing from a borehole a member having a bore therethrough positioned in the first of side by side first and second tubing strings uidly interconnected intermediate their ends and included as a part of a system for obtaining hydrocarbons from a subsurface producing formation wherein at least one perforation is provided in said first tubing string adjacent the bottom thereof and wherein the normally open bottom of the second tubing string is closed, said perforation being below said positioned member and below the point of fluid interconnection, comprising the steps of:

introducing acid dissolvable material down the first tubing string and through said member to a position below the point at which the tubing strings are interconnected to pack off the perforation and thereby develop circulating pressure in said tubing strings on pumping fluid therein;

4 pumping a pump tool down the first tubing string and attaching said pump tool to said member; pumping the pump tool with the attached member to the surface by circulation of fluid down the second tubing string and up the rst tubing string; and dissolving said acid dissolvable material by circulating acid into contact with said acid dissolvable material to open said perforation. 2. A method in accordance with claim 1 wherein the dissolvable material is a granular material.

3. A method in accordance with claim 1 wherein the dissolvable material is in the shape of a sphere.

References Cited by the Examiner UNlTED STATES PATENTS 2,796,130 6/57 Huber.

2,805,718 9/57 Tausch.

2,847,072 8/58 Lebourg 166-46 2,927,640 3/60 Kenneday 166-51 3,020,955 2/62 Tausch 166-156X 3,032,117 5/62 Tausch et al. 166-189 3,040,813 6/62 Tausch et al. 166-189 '3,095,038 6/63 Thompson et al 166-46 CHARLES E. OCONNELL, Primary Examiner. 

1. A METHOD OF REMOVING FROM A BOREHOLE A MEMBER HAVING A BORE THERETHROUGH POSITIONED IN THE FIRST OF SIDE BY SIDE FIRST AND SECOND TUBING STRINGS FLUIDLY INTERCONNECTED INTERMEDIATE THEIR ENDS AND INCLUDED AS A PART OF A SYSTEM FOR OBTAINING HYDROCARBONS FROM A SUBSURFACE PRODUCING FORMATION WHEREIN AT LEAST ONE PERFORATION IS PROVIDED IN SAID FIRST TUBING STRING ADJACENT THE BOTTOM THEREOF AND WHEREIN THE NORMALLY OPEN BOTTOM OF THE SECOND TUBING STRING IS CLOSED, SAID PERFORATION BEING BELOW SAID POSITIONED MEMBER AND BELOW THE POINT OF FLUID INTERCONNECTION, COMPRISING THE STEPS OF: INTRODUCING ACID DISSOLVABLE MATERIAL DOWN THE FIRST TUBING STRING AND THROUGH SAID MEMBER TO A POSITION BELOW THE POINT AT WHICH THE TUBING STRINGS ARE INTERCONNECTED TO PACK OFF THE PERFORATION AND THEREBY DEVEOPE CIRCULATING PRESSURE IN SAID TUBING STRINGS ON PUMPING FLUID THEREIN; PUMPING A PUMP TOOL DOWN THE FIRST TUBING STRING AND ATTACHING SAID PUMP TOOL TO SAID MEMBER; PUMPING THE PUMP TOOL WITH THE FLUID DOWN THE SECOND TUBING STRING AND UP THE FIRST TUBING STRING; AND DISSOLVING SAID ACID DISSOLVABLE MATERIAL BY CIRCULATING ACID INTO CONTACT WITH SAID ACID DISSOLVABLE MATERIAL TO OPEN SAID PERFORATION. 